Questions tagged [beam]

Questions about the theory and applications of structural elements designed to resist bending.

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How do I find Maximum deflection, the deflection at C and the location of the maximum deflection from point A [closed]

Determine the value of the Maximum deflection in kNm.cu Determine the value of the deflection at C in kNm.cu Determine the location of the maximum deflection from point "A"
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23 views

Analyze the beam shown [closed]

Analyze the beam shown on the figure and draw the stress distribution diagrams in the critical section, if the cross-section consists of two standard shapes. The shapes and the values of the ...
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1answer
22 views

Derivaiton of maximum deflection of a cantilever beam with intermediate load

I am trying to derive the maximum deflection of a cantilever beam. L is the length of the beam and a is the where force is applied. For the case 0<x<a, I use the method below and it gives me the ...
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3answers
76 views

How can deflection and spring constant of cantilever beam stack be calculated?

How can I calculate some properties of a stack of 2 bonded cantilever beams like in the image? Especially I am interested in the spring constant and deflection with force on random locations. However, ...
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22 views

Design of T-Beam

Please design a T-beam section size such that hf ≥ 125 mm, bw ≥ 200 mm, be ≥ 500 mm, d ≥ 300 mm, the concrete f'c strength is 25 MPa; the calculated concrete shear strength Vc that can be provided is ...
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1answer
47 views

How to check if bending moment diagram is correctly drawn

EDIT: I will state my test problem description and then my solution. But before that, I would like to apprise you of the absence of the actual description given during test (which happened in Zoom and ...
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1answer
19 views

Where does the equation for shear stress of a rectangular beam (3/2 V/A) come from?

I am writing a report and need to reference every equation used. I am using the equation for shear stress in a rectangular beam of tau = 3/2 * V/A but am not sure where it came from or what textbook ...
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1answer
53 views

What is meant by the rotation capacity of a cross section?

I'm reading about classification of beam cross sections here. It is said: The ratio of the ultimate rotation to the yield rotation is called the rotation capacity of the section. The yield and the ...
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58 views

Large deflection of a non prismatic cantilever beam under distributed load

Here's what I got trying to calculate the large deflection of a cantilever beam with two different cross sections under a uniformly distributed load: From the figure, the shear force is: $$ V(s) = q(...
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1answer
70 views

“Heavy-duty” or not, can my drawer slides really support this weight?

Okay, so recently I got a Dewalt 735 Thickness Planer. It's great at what it does. (It even LOOKS like it's ready to consume the tender flesh of lumber, like some twisted Victorian lumberjack... ...
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1answer
39 views

Steel beam size

I'm a customer not an engineer! I had 2 sets of drawings for a project to put in bi fold doors. The original drawing had a beam of 230mm and then the engineer sent a revision with a beam 260mm. The ...
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1answer
37 views

Linear Motion Stage with Offset Loading Problem

I'm currently developing a linear motion system which will have to withstand a large offset load (see image below). There will be two rails, each with a carriage on, which will be connected by a beam/...
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58 views

Can you use an accelerometer to measure beam deflection under static loading?

With an appropriately collocated accelerometer is it possible to retrieve lateral deflection of a beam under static loading. The beam will be loaded and then deflect until it reaches equilibrium with ...
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4answers
85 views

Swing safety: maximum load of beam (supported at one end, free with load on the other)

My husband and his dad built a fort for our two boys. Coming off of one side of the fort is a 4x6 wooden beam with a tire swing attached at the end. It is supported on one side by the fort, but not ...
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1answer
69 views

How to plot bending moment diagram from shear force diagram

With conventions that I adopted shown below I drew roughly the shear force and bending moment diagram of a simply supported beam with concentrated load at the middle. Now while drawing I drew both ...
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1answer
42 views

Optimal placement of two support points along a wooden beam

Assuming a beam that is supported at 2 points as per attached image, what would be Lc (length center) and Lo (length overhang) for maximum strength. (or load bearing capability) For actual material ...
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1answer
38 views

Estimation of Beam Displacement from Acceleration

Hi Engineering Exchange, I have a beam with pinned-pinned boundary conditions (free to rotate but not free to translate). A legacy computer analysis provided me with the maximum mid-span acceleration ...
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7answers
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Is it structurally sound to cut an I beam to a T on one end?

I'd like to confirm whether the replaced beam in the attached picture is structurally sound given the end was cut to a T instead of an I. I had a qualified structural engineer approve the work but I'm ...
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1answer
93 views

Beam for shop gantry

I have a small machine shop and need to size a beam for a gantry crane. The design is a 4 post fixed design with 2 horizontal beams running parallel across the shop ends with 1 beam to be mounted ...
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2answers
66 views

Beam buckling criterion?

If I have an I beam which I subject to some bending load, how can I calculate when the thinner middle part of the I beam will buckle? I though I could use Euler's critical load formula here, but it's ...
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1answer
64 views

Limits of Euler-Bernoulli Beam Theory for Wide Plate in Flexure?

I'm looking for established limits or rules of thumb for the validity/accuracy of Euler-Bernoulli beam equations for particularly wide "beams". For example, a simply supported rectangular ...
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1answer
22 views

Moment Arm: What dia.(3“ or 4”) Alum pole 10ft long (thickness .125) will support a load 200 or 300lb pulling at 90 degrees at the end of the pole?

I am trying to determine which diameter (3" or 4") metal pole I need to support a 20ft x 20ft pool shade tarp. I can use either steel or aluminum (aluminum preferred). The wall thickness ...
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1answer
55 views

Torsion and Bending stress calculated from deflection

I need help to check a calculation I did. I want to know if it is possible to use this method or if I am using an assumption which is wrong. Let me explain the problem, a beam with length $l$ is ...
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1answer
43 views

simply supported beam with a midspan load

First off non-engineer apologies, A plate of 5251 Aluminium is used to support the load of a centrally seated human I estimate a load of 1 kilonewton. The beam measures a length of 1000mm, 100mm wide. ...
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34 views

Deflection of a cantilever beam composed of separate (not bonded) planks Uniform load

This is related to this question It is the case of a simple cantilever beam having a uniform rectangular cross-section. cantilever beam composed of separate planks - taken from The question in the ...
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1answer
208 views

What is the difference between W, S, I, H sections?

W and H sections look pretty much the same. S and I sections have their flanges rounded. What difference does this rounding make, why would an S-section be used instead of W-section for example?
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34 views

How to choose the dimensions for a prestressed I-beam?

I need to design a simply supported symmetric I-beam (for a school problem). However, I can't find much information about the selection of the section or if there exist any standards for that. the ...
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1answer
34 views

steel beam type and size for a clothesline

I have four posts in a square formation. Posts are also square. I want to bolt a beam between two posts on the left and a beam between two posts on the right, and than run some wire between the beams. ...
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2answers
70 views

Do the floorboards in timber beam floors have a structural function?

Timber beam floors with perpendicular timber floorboards as indicated in the drawing below are common throughout northern Europe. The floorboards are nailed onto the beams and are quite substantial ...
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1answer
22 views

Centroid of unsymetric bending in T-section

Can anyone please explain how this 24 is coming while calculating the x-cordinate of the centroid.
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2answers
110 views

Maximum induced bending stress within the beam

The Maximum induced bending stress within the beam. Given that: $$\frac{My}{I}$$ The beam depth is 300mm, the width is 150mm. The beam is an I section beam with a 5mm wall thickness. My ...
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1answer
59 views

RHS beam deflection with support on one end

A 1400 mm long galv steel beam, size 40x20x2. 80 mm of the beam on one end is welded in flat position to a platform. How much weight can I put safely on the other end? What if instead of being flat ...
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22 views

Pin connection on beam - FEA analysis

I am establishing a MatLab FEA code for determining the stiffness of a structure. Diagram of the structure is added below. I have established a code for determining the stiffness of the structure, but ...
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2answers
63 views

Boundary conditions for this beam deflection problem

consider the diagram above. I know that deflection is described by the equation $$EI\frac{d^4y}{dx^4}=p(x)$$ where $L$ is the length of the beam, $E$ is the Young's module, $I$ is the moment of ...
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2answers
605 views

Degrees of freedom of an internal hinge in plane beam?

What are the degrees of freedom of an internal hinge in a plane beam? I understand that the bending moment=0, does this mean there is no slope either? Or does it have both degrees of freedom of ...
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81 views

Sign convention for deflection and slope of beam?

What is the sign convention for deflection and slope of a beam as shown in the diagram below? When I derive the formula using Euler-Bernoulli for deflection and slope myself, I end up with - ...
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1answer
56 views

Why is there a row of circular holes in this concrete beam?

The reinforced concrete beam (approximate dimensions 36" x 18") shown in the image below has a row of circular holes at 3/5ths of the height of the cross-section at approximately 300 mm centres. My ...
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1answer
29 views

Shear flow for unequal leg channel

How does the sine part i.e. $\dfrac{\ell\sin(\theta)}{2}$ appear in the calculation of shear flow ($q$)? I mean, if I'm not mistaken, the sine part is the distance from the x-axis to point D, but how ...
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2answers
36 views

Dimensioning of beam pressed by screw in assembly

I need help dimensioning a screw-beam system of a press. I built one prototype but the beam is bending too much. Below is a sketch of my press. In the middle it has a fixing screw which presses ...
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2answers
59 views

Bending moment in Euler-Bernoulli finite Element

I'm trying to calculate the bending moment distribution on a fixed-fixed Euler-Bernoulli beam. It is known that interelement nodes show different values for the bending moment. What is customary to do ...
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2answers
62 views

What is the strongest way to fasten 8020 extrusions in this arrangement?

I am making a project using 10mm aluminum extrusions. I am trying to connect all three extrusions like the picture below shows and I am going to make my own bracket (in red) out of aluminum since the ...
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1answer
70 views

Twist “buckling” critical load

I have a very long beam which is subjected to a torque (I have the moments and shear forces with respect to X along the beam). I can calculate the critical load when the beam would bend if it was ...
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2answers
67 views

Deflection and stress in a freely rotating beam

How do I calculate the deflection and stress of a beam that is rotating freely (for example in space) when a moment is being applied to it, for example by rocket motors at the ends of the beam?
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1answer
482 views

Problem while solving for the moment of a cantilever beam

As in the first image, Moment at any point between C and B should be 0. But when I try to solve it by substituting equal and opposite forces at end C so that anti-clockwise moment of $F(l-a)$ and ...
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328 views

Problem with cantilever beam and yield strength

Hey, I make a project in which I use a cantilever beam with distributed equal load across the whole beam and I'm using the formulas above to calculate the displacement, moment... My specifications ...
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1answer
76 views

Maximum I-beam girder S12x31.8 span

Does 200lb/in of load on a S12x31.8 over 15 feet seem reasonable? I'm having a tough time trusting the numbers. Two story house with an attic as below. Dotted lines show load bearing walls W1 and W2. ...
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3answers
429 views

Buckling vs. Yielding Failure of Columns

As I have been working through examples of construction projects, I've noticed that in nearly every case of a structural column (sample size considers only homogeneous material columns, no composite ...
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1answer
49 views

What criteria must apply for torsional effects on this beam to be ignored in calcs?

I'm interested in how to work out whether torsional effects can be ignored or not, in calculating the adequacy of a given steel beam in the following idealised eccentric scenario. Or, equivalently, ...
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1answer
81 views

Modification of Beam Equation for Thin Sheet

I am trying to determine the modulus of elasticity (Young's Modulus) for a rigid paper sheet. The issue I am having is that my results for the Young's Modulus change depending on what orientation (...
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2answers
125 views

Pin joint system displacement question

A pinned system comprising bars of the same material and cross-sectional area is subjected to a vertical load P. I am required to form a relationship between FAB and P. The first part of the ...

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